Photovoltaic cells, commonly known as solar cells, are well known devices for direct conversion of solar radiation into electrical energy. Generally, photovoltaic cells are grouped into arrays or modules of interconnected cells mounted on a common or shared substrate and electrically coupled to an electrical power distribution network. It is desirable to maintain a nearly perpendicular orientation of the array to the Sun's solar rays, thereby maximizing exposure of the photovoltaic cells to direct sunlight and optimizing energy yield. However, since angles of incidence of the solar rays vary according to the time of the day and the season or time of the year, it is generally necessary to provide a tracking system to position or orient the photovoltaic arrays in relation to the Sun.
Conventional tracking systems used to orient or reposition photovoltaic arrays typically move, or more precisely rotate, about a single-axis to follow the arc of the Sun across the sky. However, because the height of the Sun above the horizon changes throughout the year these one- or single-axis tracking systems are not sufficient to accurately track the Sun throughout the day or year.
Alternatively, 2-axis tracking systems have been proposed. However these have either been too complex, and therefore costly, or are insufficiently robust to support the weight of the photovoltaic arrays or to withstand the often harsh environmental conditions to which photovoltaic arrays and their tracking systems are frequently exposed.